JP2004184895A - Stereoscopic image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the number of parallaxes in the lateral direction on a screen runs short, and the resolution balance in the longitudinal and lateral directions on the screen is bad in a stereoscopic image display device. <P>SOLUTION: A double refractive film laminate having a double refractivity as an optical pixel shifting means is arranged between an image display panel and an optical image selecting means such as a slit array, then, two lines are displayed as one line, then, the lateral parallax information is doubled. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

で表される。従って、フィルム厚ｄにおける異常光線のシフト量ｐは、
【００３８】
【数２】

となる。
【００３９】
図４は、画素１０４の配列と画素の光学シフト方向をｚ軸方向、即ち、観察者から見た図である。
【００４０】
本実施形態においては、画素は１行おきに半画素ｘ軸方向にずれたデルタ配列構造を用いている。
【００４１】
複屈折フィルム積層体により、ｉ＋１行、ｉ＋３行の画素が光学的にｙ軸方向へ１画素分シフトする。即ち、ｉ行目とｉ＋１行目が重なり、ｉ＋２行目とｉ＋３行目が重なって見える。画素構造がデルタ配列となっているため、１軸方向の画素ずらし操作により、それぞれｉ行、ｉ＋２行の画素間に下の行の画素を重ね、補間表示することが可能となる。
【００４２】
図５は、本実施例における画素と画像情報の割り当て方法を模式的に示した図である。
【００４３】
比較のために、まず、図１４に従来の画素と画像情報の割り当て方法を示した。図１４においては、横方向視差数を４、縦方向視差数を０に設定した場合を示している。
【００４４】
ＩＰ方式においては、図１４の例では、対応する１つのスリットを通して４つの画素を見ることができるようにし、４画素を１組とする。この４つの画素は、４つの方向から見たときの映像情報の各１ドットに相当している。
【００４５】
ｉ行ｊ列、ｉ＋２行ｊ列の画素については第１の視差画像（番号１とする）に基づく画像情報を割り当て、以下列方向に４つの画像情報を割り当てている（番号１〜４）。これらの番号１〜４の画素が１組となり、４つの視差に対応する。
【００４６】
また、ｉ＋１行ｊ＋１列、ｉ＋３行ｊ＋１列の画素についてはｉ行ｊ列から半画素ずれた視線方向からの画像に基づく情報（１’）を割り当てている。画素の表示位置は変化しないので、それぞれの画素に表示する画像情報は各々の画素に割り当てられた画像について、画素の位置に相当する箇所をサンプリングした値である。
【００４７】
一方、図５においては、ｉ＋１、ｉ＋３行の画素はそれぞれｉ、ｉ＋２行の位置にシフトするため、シフト後の画素位置において画像情報をサンプリングしなくてはならない。例えば、ｉ＋１行ｊ＋１列の位置において表示される画像情報２は、ｉ行ｊ列とｉ行ｊ＋２列の画素境界位置においてサンプリングされた画像情報である。
【００４８】
即ち、番号１〜８の８つの画素を１組として、８つの視差に対応する画像を表示する。従って、図５において、ｉ行ｊ列〜ｉ＋１行ｊ＋７列が１組を成し、ｉ＋１行ｊ＋９列〜ｉ行ｊ＋１６列が１組を成す。
【００４９】
ここで、ｊ＋８列に存在する画素４０１は、ｊ列からｊ＋７列の画素群を用いて視差番号を割り当てたｋ番目の視差画像群と、ｊ＋９列以降から始まるｋ＋１番目の視差画素群の境界中央部に位置している。そのため、例えば画素４０１に第ｋ視差画像群に属する視差情報を与えると、第ｋ＋１視差画像群に対応するスリットアレイ開口部から画素４０１を観測した場合に、誤った画像情報（偽像）が表示されてしまう。このため、画素４０１に相当する視差画像境界部の画素列は図５に示したように黒表示とすることができる。
【００５０】
図６は、本実施例における透過型液晶パネルの表示駆動タイミング例を示した図である。
【００５１】
行方向の順次走査に対しては、ｉ行とｉ＋１行、ｉ＋２行とｉ＋３行が表示面では同一行に表示されるため、同時刻に走査されることが望ましい。ここでは、図に示すように、２ライン同時駆動を行なうために、ｉ行とｉ＋１行、ｉ＋２行とｉ＋３行には同一の走査開始信号が印加される。さらに、画素列方向に点順次走査を行なう場合には、ｉ行とｉ＋２行、ｉ＋１行とｉ＋３行は半画素ずれているため、クロックＣＬＫとその反転クロックを１組として用いることでクロック周波数の増大を防ぐことが可能となる。
【００５２】
本実施形態の構成において、スリットアレイ１０２を出射する光線の様子を図７に示す。また、従来の構成における様子を図１５に示す。ここでは、簡単のため、画素構造以外の液晶パネルの構成部材、複屈折フィルム積層体等は図示省略している。本実施例においては縦方向視差を設けていないため、光学的画像選択手段は開口部をスリット状としたスリットアレイであり、図１６と同様、開口部６０１が視線方向番号を割り当てた１組の画素群の中央部に位置している。
【００５３】
図１５は、やはり４画素を１組とし、横方向のみに視差を与えた例である。即ち、観察者が横方向に移動すると、４方向からの像を見ることができるが、縦方向には視差はなく、観察者が縦方向に移動しても画像に変化がない。
【００５４】
この場合、各行から出射した光が、各々、スリット１０２を通して観察者に届くことになる。４画素が１組となるので、４つの方向から見た場合の画像が表示される。
【００５５】
これに対して、図７に示すように、本実施形態によると、やはり横方向に４画素を１組とするが、画像シフト手段により、２つの行が重なるので、８つの画素を１組とすることができる。即ち、８方向の視線方向に対応した画像（１〜８）が、画素とスリット開口部を結ぶ線分上に光線として出射している。図１５と比較すると、縦方向の出射密度が１／２に減少するものの、ｉ行、１＋２行における横方向の光線本数が倍増していることが分かる。
【００５６】
図１５（従来例）の場合と図７（本実施形態）との表示精細度を比較すると、従来例の横方向視差数は１行あたり４であるが、上下の画素が１／２画素ずれており、視差情報が入れ子になっているため、実効的な視差数、画面上下方向の空間周波数は実効的にほぼ等しい。しかしながら、これらデルタ配列の画素にＲＧＢ三原色のカラー情報を与えた場合、従来の構成では画素が完全分離配置しているため、色が分離して見え易い。これに対し、本実施形態においては、ＲＧＢ三原色画素が重なり合って表示されるため、色の分離が認識されにくい、という利点が生じる。
【００５７】
図８に、本実施形態における望ましいカラーフィルタ配列の例を示す。
【００５８】
図８においては、ｉ＋１行とｉ＋２行のように、隣接する画素の色配列を一致させている（７０１）。また、縦方向には、カラー配列がＲＧＢとしてある（７０２）。
【００５９】
このような配列とすることで、シフト後の横方向カラー配列はＲＧＢ、ＲＧＢと入れ子構造になる。同時に、同一の視線方向における画像情報を表示する、縦方向画素のカラー配列もＲＧＢ、ＲＧＢと順次配列される。従って、行方向、列方向どちらの方向においてもカラーバランスに優れており、色の分離やカラーシフトを認識しにくくすることが可能となる。
【００６０】
以上、上記の説明においては、液晶パネル１０１の偏光板透過軸をｘ、ｙ軸方向としたが、実際には液晶の視野角依存性のため、偏光板透過軸をｘｙ軸に対し４５°方位とする例が多く見られる。この場合、出射側偏光板１０６ｂと複屈折フィルム積層体１０３間に、λ／２層を新たに設け、λ／２層の位相軸を出射側偏光板１０６ｂの偏光透過軸とｘ軸を２分する方位に配置することで、λ／２の出射偏光軸をｘ軸方向とすることができ、以降は上記と同じ構成で同様の効果が得られる。λ／２層は複屈折フィルム１０９と同様、ポリカーボネート、アートンなどを材質とする複屈折フィルムを用いることができる。
（実施形態２）
本発明の第２の実施形態について図９〜図１３を用いて説明する。
【００６１】
図９は、第１の実施形態における図２と同様、立体画像表示装置をｘ軸方向の側面からみた部分断面図である。本実施形態では、画像表示手段として自発光型の有機ＥＬパネル８０１を、光学的画像選択手段としてレンチキュラーレンズアレイ８０２を用いている。有機ＥＬパネル８０１と、光学的画像選択手段であるレンチキュラーレンズアレイ８０２の間に、複屈折フィルム積層体１０３が光学的画素位置シフト手段として設けられている。複屈折フィルム積層体１０３において、実施形態１に示した機能を有する複屈折フィルム層が８０３、８０６の２層構造になっていることを特徴としている。
【００６２】
複屈折フィルム８０３、８０６は、屈折率主軸の向きが異なっており、ｙ軸方向に偏光軸を持つ１段目の複屈折フィルム８０３によりｘ軸方向の光学シフト、２段目の複屈折フィルム８０６によりｙ軸方向への光学シフトが生じる。
【００６３】
複屈折フィルム８０３と８０６の間にはλ／２複屈折フィルム８０４、８０５が２層設けられており、波長分散を低減するために、偏光回転操作を２回行なうことで９０°の偏光回転操作を行なう。
【００６４】
有機ＥＬパネル８０１は、発光層となる画素１０４を有しており、画像情報に応じて所定の光強度、色を有する光８０７を発光する。発光光８０７は非偏光であるので、基板の光出射側にｘ軸方向に偏光透過軸を有する偏光板１０６ｂが設けられており、出射光１１３はｘ軸方向に偏光軸を有する偏光光となる。
【００６５】
出射光１１３は、光学的画素位置シフト手段である複屈折フィルム積層体１０３に入射する。
【００６６】
ｉ行、ｉ＋２行の画素を出射した偏光１１３ａ、１１３ｃは、第１の実施形態と同様に、偏光回転層１０８によって９０°の偏光回転操作を受け、偏光軸がｙ軸方向に変換される。次段の複屈折フィルム８０３、８０６は、ｙ軸方向に偏光軸を持つ１段目の複屈折フィルム８０３によりｘ軸方向の光学シフト、２段目の複屈折フィルム８０６によりｙ軸方向への光学シフトが生じる。
【００６７】
複屈折フィルム８０３と８０６間にあるλ／２複屈折フィルム８０４、８０５の２層を用いた偏光回転操作の合成により９０°の偏光回転操作を行なう。
【００６８】
位相軸の方位はｘｙ軸面内において、ｘ軸から６７．５°、２２．５°の方位に設置することで、ｘ軸方向の偏光軸は光入射時に０°から複屈折フィルム８０３出射時に１３５°、複屈折フィルム８０６出射時に−９０°となり、ｙ軸方向の偏光軸は光入射時に９０°から４５°を経て０°に変換され、偏光軸方位の交換が行なわれる。このように、λ／２複屈折フィルム層を多段構成として９０°偏光回転操作を行なうことで、λ／２条件から外れた波長成分の位相補償が行なわれるため、λ／２層１段構成、４５°配置による偏光軸９０°回転操作よりも広帯域とすることができる。
【００６９】
図１０は、本実施形態における複屈折フィルム積層体１０３の複屈折フィルム８０３、８０６の光学配置を示した図である。
【００７０】
複屈折フィルム８０３では、ｘ軸方向の光学シフトを行なうために、異常光線屈折率ｎ_ｅ１の方位は、ｘｚ平面内にあり、ｚ軸に対して角度θ_１を成している。一方、複屈折フィルム８０６においては、実施例１と同様ｙ軸方向の光学シフトを行なうため、異常光線屈折率ｎ_ｅ２の方位は、ｙｚ平面内にあり、ｚ軸に対して角度θ_２を成している。
【００７１】
図１１は、本実施形態における画素と視線情報の割り当て方法を模式的に示した図である。
【００７２】
ここでは、説明の簡単のため、横方向視差数を４、縦方向視差数を０とする例を示す。また、画素配列は格子状をなしており、いわゆる正方配列を用いる。
【００７３】
ｉ＋１行、ｉ＋３行における画素は、複屈折フィルム８０３、８０６による２段階の画素シフトを受け、ｉ行、ｉ＋２行の画素間に移動して見える。即ち、ｉ行ｊ列の画素において表示される視線方向の画像情報１と、ｉ行ｊ＋１列の画素において表示される画像情報３の間に、ｉ＋１行ｊ列の画素において表示される画像情報２が重なり挿入される。従って、ｉ＋１行ｊ列の画素に表示するべき画像情報２は、ｉ行ｊ列とｉ行ｊ＋１列との画素境界においてサンプリングされた画像情報を表示することになる。
【００７４】
図１２は、レンチキュラーレンズアレイ８０２を出射する光線の様子を示した図である。簡単のため、図７と同様、画素構造以外の有機ＥＬパネルの構成部材、複屈折フィルム積層体等は図示省略している。
【００７５】
ここでは縦方向視差を設けていないため、光学的画像選択手段はレンチキュラーレンズアレイであり、レンズ中心が視差番号を割り当てた画素群の中央部に位置している。
【００７６】
８方向の視線方向に対応した画像（１〜８）が、画素とレンズ中心を結ぶ線分上に光線として出射している。
【００７７】
これを、画素シフトを行なわない従来例と比べると、視線方向１枚当たりの縦解像度は１／２となっているが、視線本数は４本から８本に倍増していることが分かる。
【００７８】
例えば、有機ＥＬパネルの横方向画素数を１６００、縦方向画素数を１２００とすると、従来構成では、横方向視差数４、視線方向あたりの表示画素数は４００×１２００となり、アスペクト比４：３のパネルについて横対縦の解像度比は１：４であるのに対し、本実施例では、横方向視差数が８に増加し、視線方向あたりの表示画素数は４００×６００、横対縦解像度比は１：２と、横方向と縦方向の解像度バランスが向上していることが分かる。
【００７９】
なお、実施形態１において述べたように、画素群の境界に位置する画素４０１には黒表示を行い、偽像の発生を防止できる。
【００８０】
図１３は、カラー画素を用いた場合における望ましいカラー配列を示した図である。
【００８１】
格子状にカラー配列が形成される場合、横方向の画素幅と縦方向の画素長を１：３として、縦ストライプ型の構造を取る場合が多い。本実施形態においては、ｉ＋１行の画素がｉ行の画素間に配置されるため、例えばｉ行ｊ列、ｉ＋１行ｊ列、ｉ行ｊ＋１列、ｉ＋１行ｊ＋１列の順にＲＧＢ三原色が入れ子構造を取ることが望ましい。また、列方向においても、ｉ行、ｉ＋２行、ｉ＋４行の順にＲＧＢ三原色が入れ子構造となっていることが望ましい。従って、このような画素配列は、図１３に示すような、行方向、列方向に隣接する画素の色が異なる、いわゆる斜めストライプ構造を取っていることが望ましい。
【００８２】
なお、以上の説明においては、説明の簡単のために縦方向の視差数を０としたため、光学的画像選択手段としてスリットアレイとレンチキュラーレンズアレイを挙げたが、縦方向に視差数を設けた場合は、これらはそれぞれピンホールアレイとレンズアレイとすれば良い。
【００８３】
【発明の効果】
以上述べたように本発明の実施の形態によれば、立体画像表示装置において重要な横方向視差数を増大させ、視線あたりの画像における縦方向と横方向の解像度バランスを向上させることで、高品位な立体画像を表示することが可能となる。
【図面の簡単な説明】
【図１】本発明の第１の実施形態に関わる構成を側面から見た断面図
【図２】本発明の第１の実施形態に関わる構成を側面から見た断面図
【図３】本発明の第１の実施形態における複屈折フィルムの光学配置を示した図
【図４】本発明の第１の実施例において画素配列と画素の光学シフト方向をｚ軸方向から見た図
【図５】本発明の第１の実施例において画素と画像情報の割り当て方法を模式的に示した図
【図６】本発明の第１の実施例において透過型液晶パネルの表示駆動タイミング例を示した図
【図７】本発明の第１の実施例においてスリットアレイを出射する光線の様子を示した図
【図８】本発明の第１の実施形態における望ましいカラーフィルタ配列の例を示した図
【図９】本発明の第２の実施形態に関わる構成を側面から見た断面図
【図１０】本発明の第２の実施形態において複屈折フィルム積層体の複屈折フィルムの光学配置を示した図
【図１１】本発明の第２の実施形態において画素と視線情報の割り当て方法を模式的に示した図
【図１２】本発明の第２の実施形態においてレンチキュラーレンズアレイを出射する光線の様子を示した図
【図１３】本発明の第２の実施形態における望ましいカラーフィルタ配列の例を示した図
【図１４】従来の構成において、画素と画像情報の割り当て方法を示した図
【図１５】従来の構成において、スリットアレイを出射する光線の様子を示した図
【図１６】ＩＰ法の表示原理を説明する図
【符号の説明】
１０１・・・透過型液晶パネル
１０２・・・スリットアレイ
１０３・・・複屈折フィルム積層体
１０４、４０１・・・画素
１０５・・・光透過基板
１０６ａ、１０６ｂ・・・偏光板
１０８、８０４、８０５・・・λ／２波長フィルム（偏光回転層）
１０９、８０３、８０６・・・複屈折フィルム（光学シフト層）
１１０・・・ガラス基板
１１１・・・光源光
１１２、１１３ａ、１１３ｂ、１１３ｃ、１１３ｄ・・・偏光光
１１４ａ、１１４ｂ・・・入射光
１１５・・・出射光
６０１・・・開口部
７０１・・・隣接画素の組
７０２・・・カラー配列の組
８０１・・・有機ＥＬパネル
８０２・・・レンチキュラーレンズアレイ
８０７・・・発光光
１５００・・・立体画像表示装置
１５０１・・・表示オブジェクト
１５０２・・・観測者
１５０３、１５０５・・・表示すべきオブジェクト位置
１５０４・・・表示情報
１５０６ａ、１５０６ｂ、１５０６ｃ、１５０６ｄ・・・視線方向
１５０７ａ、１５０７ｂ、１５０７ｃ、１５０７ｄ・・・表示画面上におけるオブジェクト情報表示位置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a three-dimensional image display device.
[0002]
[Prior art]
As a method of displaying a stereoscopic image using a two-dimensional display device, an optical system that combines and displays images from many viewing directions on an image display surface and selectively visually recognizes a corresponding image according to a viewer's viewpoint position. An integral photography method (hereinafter referred to as an IP method) provided with a dynamic image selection means has been proposed.
[0003]
FIG. 16 shows the display principle of the IP method. Here, the z-axis is taken from the display device toward the observer 1502, the x-axis is the horizontal (left-right) direction in the display surface, and the y-axis is the vertical (vertical) direction. That is, FIG. 16 is a top view as viewed from the y-axis direction.
[0004]
The stereoscopic image display device 1500 has a structure in which a slit array 102 having openings substantially equal to the pixel pitch in an array is provided in front of the display surface (observer side) as optical image selection means.
[0005]
A light ray passing through the opening of the slit array 102 is emitted from the pixel 104, and an intersection of the virtually arranged display object 1501 with the surface closest to the observer is obtained as an object position 1503 to be displayed. The texture is generated as pixel display information 1504. In FIG. 16, the display information corresponding to the intersection of the display objects is schematically indicated by the same symbol.
[0006]
Since the observer 1502 observes the pixel 104 through the slit array 102, the visible pixel 104 is limited to a part and only the image viewed from the viewpoint direction can be selectively viewed.
[0007]
In the stereoscopic image display method based on the IP method, the greater the number of parallaxes per unit angle in the viewpoint range (viewing area) in which the observer visually recognizes the stereoscopic image, the more smoothly the parallax information of the display object can be expressed, so that the stereoscopic display quality is low. improves. On the other hand, the finer the pitch of the optical image selecting means, for example, the slit pitch, the higher the resolution of the image that can be observed at a certain viewpoint, and the higher the display quality of the image. Therefore, it is desirable that the number of images, that is, the number of pixels, which can be allocated to the slit is large and the slit pitch is small. In other words, it is desirable that the number of pixels on the image display surface is large and the pixel pitch is fine.
[0008]
By the way, there is a device which provides a display device with high resolution using a birefringent plate. (Patent Document 1) Here, an example of a three-dimensional image display device that selectively emits right-eye and left-eye light by passing light from a display device through a birefringent plate using polarized light is disclosed. It is shown as In addition, an example as an optical low-pass filter is shown.
[0009]
[Patent Document 1]
JP-A-9-152572
[0010]
[Problems to be solved by the invention]
Regarding the number of parallaxes in the stereoscopic image display device, more importance is attached to the number of parallaxes in the horizontal (left / right) direction than in the vertical (up / down) direction with respect to the image display surface. The reason is that the vertical disparity information is provided to correspond to the vertical motion parallax of the observer, while the horizontal disparity information is added to the left and right motion parallax in addition to the horizontal motion parallax. This is because it is necessary to deal with eye parallax. In addition, the fact that the range of motion of the observer is generally wider in the left-right direction than in the up-down direction is also a reason why much emphasis is placed on the number of parallaxes in the horizontal direction.
[0011]
However, the definition of the image display panel used as the image display means is limited by the manufacturing process. Further, in a normal image display panel, pixels are formed at an equal pitch in the vertical direction and the horizontal direction of the image display surface, or in the vertical and horizontal dimension ratio of 3: 1 as RGB three primary color pixels. If the numbers are set to different values, the number of pixels per screen will be significantly different in the vertical and horizontal directions.
[0012]
For example, in a case where a liquid crystal panel having 1600 horizontal pixels, 1200 vertical pixels, and a screen aspect ratio of 4: 3 is used as an image display unit, setting the number of parallaxes in the horizontal direction to 16 and the number of parallaxes in the vertical direction to one screen The number of pixels per pixel is as follows: horizontal pixel number = 1600/16 = 100, vertical pixel number = 1200/4 = 300. Therefore, the spatial frequency that can be displayed in the horizontal direction of the screen is 1/4 of that in the vertical direction of the screen. Normally, in the two-dimensional display, an image format in which the display spatial frequencies in the vertical and horizontal directions of the screen are matched or an image format in which the spatial frequency is high in the horizontal direction is adopted. When a significant difference occurs in the spatial frequency of the image, the display image deteriorates due to the sub-sampling even in a case where a normal two-dimensional display is converted to a three-dimensional display.
As described above, in the conventional configuration, the number of pixels in the horizontal direction of the screen is insufficient compared with the number of pixels in the vertical direction of the screen.
[0013]
[Means for Solving the Problems]
An embodiment of the present invention is an image display unit in which a plurality of pixels are arranged in a plurality of rows, and is provided separately on the image display unit, the pixels on the image display unit are divided into a plurality of sets, and A pixel selecting means for selectively transmitting light, provided between the image display means and the pixel selecting means, having a birefringent property, optically shifting a part of the pixels, and A stereoscopic image display device comprising: a pixel shift unit that sets one of the two rows on the display unit as a pair.
[0014]
The pixel selection means may be a pinhole array or a lens array.
[0015]
The pixel selection means may be a slit or a lenticular lens array.
[0016]
Pixels located at the boundaries of the plurality of sets of the pixels can be displayed in black.
[0017]
The pixels on the image display means may form a three-primary-color delta array, and the three primary colors may be sequentially circulated and arranged in the vertical direction, and the same color may be adjacent to each other in the adjacent but not paired rows.
[0018]
The pixels on the image display means may be arranged in a square arrangement of three primary colors, and the primary colors may be sequentially circulated in the vertical direction, and the same colors may be arranged in an oblique stripe arrangement.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the stereoscopic image display device according to the present invention will be described in detail. However, the configuration of the present invention is not limited to the embodiment described below, and it goes without saying that various combinations of the components of the configuration described in the embodiment and the example of the invention can be adopted. . For simplification of description, the same members are given the same numbers in a plurality of drawings.
(Embodiment 1)
Hereinafter, a first embodiment of the present invention will be described.
[0020]
FIG. 1 is a diagram for explaining the outline of the present embodiment. In the drawings, the z-axis is taken from the display device toward the observer, the x-axis is the horizontal (left-right) direction in the display surface, and the y-axis is the vertical (up-down) direction.
[0021]
The stereoscopic image display device includes an image display unit, for example, a liquid crystal display device 101, and a slit array 102 in which openings substantially equal to the pixel pitch are provided in an array as an optical image selection unit in front of the display surface (observer side). The optical pixel position shift means 109 is provided between them.
[0022]
Light rays passing through the openings of the slit array 102 are emitted from the pixels 104, and the surface texture of the display object is generated as display information of the pixels.
[0023]
FIG. 2 is a diagram showing an outline of the optical pixel position shifting means. FIG. 3 is a cross-sectional view of the stereoscopic image display device viewed from the side in the x-axis direction, with a light source (not shown) side on the left of the paper and an observer (not shown) on the right of the paper. In the present embodiment, a structure in which a birefringent film laminate 103 is provided as an optical pixel position shift unit between a transmission type liquid crystal panel 101 as an image display unit and a slit array 102 as an optical image selection unit. Has become.
[0024]
The transmissive liquid crystal panel 101 has a structure in which a pixel 104 having a liquid crystal layer sandwiched between light transmitting substrates 105 is formed, and polarizing plates 106a and 106b are provided before and after the substrate. In the pixel 104, electric charge is written and held for each pixel according to image information, and the alignment state of the liquid crystal is controlled by the electric charge.
[0025]
The birefringent film laminate 103 includes a polarization rotating layer 108 and a birefringent film 109.
[0026]
The birefringent film 109 is a uniaxial birefringent film having a main axis of the refractive index in a predetermined direction. Desired optical characteristics can be obtained by stretching and orienting a polycarbonate or ARTON manufactured by JSR Corporation or a polymer liquid crystal polymer layer. Although the optical characteristics of the birefringent film 109 will be described later, the birefringence of the birefringent film 109 causes a difference in the light traveling direction depending on the polarization direction of the incident light.
On the liquid crystal panel 101 side of the birefringent film 109, a polarization rotation layer 108 is provided. The polarization rotation layers 108 are provided every other row corresponding to the pixel rows of the liquid crystal panel 101. For example, the polarization rotation layer 108 is provided in a portion corresponding to the even-numbered row of the liquid crystal panel 101, and is not provided in the odd-numbered row.
[0027]
The polarization rotation layer 108 is a so-called λ / 2 wavelength film layer, and a birefringent layer having a retardation of 200 to 300 nm, which is a half wavelength of visible light, has a phase axis in a 45 ° direction that divides the xy axis into two. It is an optical layer.
[0028]
Such an optical layer is provided with birefringence by subjecting an optical polymer having birefringence, such as a polymer polymer liquid crystal, to an optically isotropic transparent substrate and subjecting it to alignment treatment by stress or the like, thereby providing UV irradiation or the like. It can be formed by processing so as to leave the birefringent layer in a stripe shape by a thermal and patterning process.
[0029]
In the non-polarized light source light 111, only the component in the y-axis direction, which is the polarization transmission axis of the incident-side polarizing plate, is transmitted, and enters the pixel 104. When the polarized light passes through the pixel 104, the polarization state changes according to the alignment state of the liquid crystal layer, and only the polarized light component 113 in the x-axis direction, which is the polarization transmission axis of the polarizing plate 106b provided on the emission side, is emitted. The change in the orientation of the liquid crystal layer is nothing but controlling the transmission intensity of the output polarized light component 113.
[0030]
Of the polarized light 113 emitted from the polarizing plate 106b, the polarized light component 113b emitted from the pixels i + 1 and i + 3 passes through the polarization rotating layer 108 provided on the light incident surface of the birefringent film laminate 103 every other pixel. Then, the polarization axis rotates 90 ° from the x axis in the y axis direction.
[0031]
The polarization axis of the light emitted from the i-th row and the (i + 2) -th row of pixels is in the x-axis direction, and coincides with the ordinary ray refractive index direction of the birefringent film 109. Therefore, the incident light 114a goes straight as ordinary rays. On the other hand, the emission components of the pixel i + 1 row and i + 3 row that have been rotated by 90 ° by the polarization rotation layer 108 have a polarization axis in the y-axis direction. Therefore, in the birefringent film 109, the traveling direction of light as an extraordinary ray shifts in the y-axis direction. That is, the birefringent film 109 has a function of an optical shift layer that shifts the optical path in position with respect to the incident polarized light component and emits the light.
[0032]
After the two polarized light components exit the birefringent film 109, they travel straight again in the z-axis direction. For this reason, the outgoing lights of the i-th and i + 1-th rows and the i + 2 and i + 3-th rows of the pixels are combined, and are emitted from the openings provided in the slit array 102.
[0033]
In this example, an optically isotropic glass substrate (or a plastic substrate such as PMMA or Arton) 110 is provided to support the slit array 102 and the birefringent film laminate 103.
[0034]
FIG. 3 is a diagram showing an optical arrangement of the birefringent film 109.
[0035]
The birefringent film 109 has uniaxial birefringence, and has a refractive index ellipsoid and a principal axis of the refractive index, and an ordinary ray refractive index of n. _o , The extraordinary ray refractive index _e As shown in the figure. Extraordinary ray refractive index n _e Is in the yz plane and forms an angle θ with respect to the z-axis. Here, the film thickness is d.
[0036]
Of the light incident perpendicular to the birefringent film 109, the polarization component in the x-axis direction has a refractive index n _e Therefore, the azimuths of the electric displacement vector D and the electric field vector E (not shown) coincide with each other as ordinary rays and go straight. On the other hand, the electric displacement vector D of the polarization component in the y-axis direction goes straight, while the direction of the electric field vector E is the contact point between the wavefront plane having the electric displacement vector D as a normal and the refractive index ellipsoid and the center of the ellipsoid. , In the yz plane and traveling in a direction forming an angle α with respect to the z-axis.
The relationship between θ and α is
[0037]
(Equation 1)

Is represented by Therefore, the shift amount p of the extraordinary ray at the film thickness d is
[0038]
(Equation 2)

It becomes.
[0039]
FIG. 4 is a diagram showing the arrangement of the pixels 104 and the optical shift direction of the pixels as viewed in the z-axis direction, that is, as viewed from an observer.
[0040]
In the present embodiment, the pixels use a delta array structure in which every other row is shifted by half a pixel in the x-axis direction.
[0041]
The pixels in the (i + 1) th row and the (i + 3) th row are optically shifted by one pixel in the y-axis direction by the birefringent film laminate. That is, the i-th row and the (i + 1) -th row overlap, and the (i + 2) -th row and the (i + 3) -th row overlap. Since the pixel structure is in a delta arrangement, the pixel in the lower row can be overlapped between the pixels in the i-th row and the i + 2 row by performing the pixel shifting operation in the one axis direction, and interpolation display can be performed.
[0042]
FIG. 5 is a diagram schematically illustrating a method of assigning pixels and image information in the present embodiment.
[0043]
For comparison, first, FIG. 14 shows a conventional method for assigning pixels and image information. FIG. 14 illustrates a case where the number of parallaxes in the horizontal direction is set to 4 and the number of parallaxes in the vertical direction is set to 0.
[0044]
In the IP system, in the example of FIG. 14, four pixels can be seen through one corresponding slit, and four pixels are set as one set. These four pixels correspond to one dot of the video information when viewed from four directions.
[0045]
Image information based on the first parallax image (number 1) is assigned to the pixels in the i-th row and j-th column and the i + 2 row and j-th column, and four pieces of image information are assigned in the column direction (numbers 1 to 4). The pixels of numbers 1 to 4 form a set, and correspond to four parallaxes.
[0046]
Information (1 ′) based on an image from the line of sight shifted by half a pixel from the i-th row and the j-th column is assigned to the pixels at the i + 1-th row and the j + 1-th column and the i + 3 and the j + 1-th column. Since the display position of the pixel does not change, the image information to be displayed on each pixel is a value obtained by sampling a portion corresponding to the pixel position in the image assigned to each pixel.
[0047]
On the other hand, in FIG. 5, since the pixels in the i + 1 and i + 3 rows are shifted to the positions in the i and i + 2 rows, the image information must be sampled at the shifted pixel positions. For example, the image information 2 displayed at the position of the (i + 1) th row and the (j + 1) th column is image information sampled at the pixel boundary position of the (i) th row and the (j) th column.
[0048]
That is, an image corresponding to eight parallaxes is displayed with eight pixels of numbers 1 to 8 as one set. Therefore, in FIG. 5, the i-th row and j-th column to i + 1-th row and j + 7-column form one set, and the i + 1-th row and j + 9 to i-th row j + 16 columns form one set.
[0049]
Here, the pixel 401 present in the j + 8 column is the center of the boundary between the k-th parallax image group to which the parallax numbers are assigned using the pixel groups from the j-th column to the j + 7-th column and the k + 1-th parallax pixel group starting from the j + 9-th column. Located in the department. Therefore, for example, when disparity information belonging to the k-th parallax image group is given to the pixel 401, when the pixel 401 is observed from the slit array opening corresponding to the (k + 1) -th parallax image group, incorrect image information (false image) is displayed. Will be done. For this reason, the pixel row at the parallax image boundary corresponding to the pixel 401 can be displayed in black as shown in FIG.
[0050]
FIG. 6 is a diagram showing an example of display drive timing of the transmission type liquid crystal panel in the present embodiment.
[0051]
In the sequential scanning in the row direction, the i-th row and the i + 1-th row and the i + 2 row and the i + 3-th row are displayed on the same row on the display surface. Here, as shown in the figure, the same scanning start signal is applied to the i-th row and the i + 1-th row, and the i + 2 row and the i + 3-th row in order to simultaneously drive two lines. Further, when dot sequential scanning is performed in the pixel column direction, the i-th row and the i + 2 row and the i + 1-th row and the i + 3 row are shifted by half a pixel. It is possible to prevent an increase.
[0052]
FIG. 7 shows a state of the light beam emitted from the slit array 102 in the configuration of the present embodiment. FIG. 15 shows a state in a conventional configuration. Here, for the sake of simplicity, components of the liquid crystal panel other than the pixel structure, a birefringent film laminate, and the like are not shown. In the present embodiment, since no vertical parallax is provided, the optical image selecting means is a slit array having a slit-like opening, and a set of openings 601 is assigned a viewing direction number as in FIG. It is located at the center of the pixel group.
[0053]
FIG. 15 shows an example in which a set of four pixels is used and parallax is given only in the horizontal direction. That is, when the observer moves in the horizontal direction, images from four directions can be seen, but there is no parallax in the vertical direction, and there is no change in the image even when the observer moves in the vertical direction.
[0054]
In this case, the light emitted from each row reaches the observer through the slit 102. Since four pixels form one set, images when viewed from four directions are displayed.
[0055]
On the other hand, as shown in FIG. 7, according to the present embodiment, four pixels are also set as one set in the horizontal direction. However, since two rows are overlapped by the image shift unit, eight pixels are set as one set. can do. That is, images (1 to 8) corresponding to eight viewing directions are emitted as light rays on a line segment connecting the pixel and the slit opening. Compared to FIG. 15, it can be seen that the number of light beams in the horizontal direction in the i-th row and the 1 + 2 row is doubled, although the emission density in the vertical direction is reduced by half.
[0056]
When the display definition of FIG. 15 (conventional example) is compared with that of FIG. 7 (this embodiment), the number of parallaxes in the horizontal direction in the conventional example is 4 per row, but the upper and lower pixels are shifted by 1/2 pixel. Since the parallax information is nested, the effective number of parallaxes and the spatial frequency in the vertical direction of the screen are substantially equal. However, when the color information of the three primary colors RGB is given to these pixels in the delta arrangement, the pixels are completely separated and arranged in the conventional configuration, so that the colors are easily separated and seen. On the other hand, in the present embodiment, since the RGB primary color pixels are displayed in an overlapping manner, there is an advantage that color separation is hardly recognized.
[0057]
FIG. 8 shows an example of a desirable color filter array in the present embodiment.
[0058]
In FIG. 8, adjacent pixels have the same color arrangement as in the (i + 1) -th row and the (i + 2) -th row (701). In the vertical direction, the color arrangement is RGB (702).
[0059]
With this arrangement, the shifted horizontal color arrangement has a nested structure of RGB and RGB. At the same time, the color arrangement of the pixels in the vertical direction, which displays image information in the same viewing direction, is also sequentially arranged as RGB and RGB. Therefore, the color balance is excellent in both the row direction and the column direction, and it is possible to make it difficult to recognize color separation and color shift.
[0060]
In the above description, the transmission axis of the polarizing plate of the liquid crystal panel 101 is defined as the x and y-axis directions. However, in practice, the transmission axis of the polarizing plate is oriented at 45 ° with respect to the xy axis because of the viewing angle dependence of the liquid crystal. There are many examples. In this case, a λ / 2 layer is newly provided between the output side polarizing plate 106b and the birefringent film laminate 103, and the phase axis of the λ / 2 layer is divided into two by the polarization transmission axis and the x axis of the output side polarizing plate 106b. By arranging them in the azimuth directions, the output polarization axis of λ / 2 can be set in the x-axis direction, and thereafter, the same effect can be obtained with the same configuration as described above. As with the birefringent film 109, a birefringent film made of polycarbonate, ARTON, or the like can be used for the λ / 2 layer.
(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIGS.
[0061]
FIG. 9 is a partial cross-sectional view of the stereoscopic image display device viewed from the side in the x-axis direction, similarly to FIG. 2 in the first embodiment. In this embodiment, a self-luminous organic EL panel 801 is used as an image display unit, and a lenticular lens array 802 is used as an optical image selection unit. The birefringent film laminate 103 is provided as an optical pixel position shift unit between the organic EL panel 801 and a lenticular lens array 802 as an optical image selection unit. The birefringent film laminate 103 is characterized in that the birefringent film layer having the function shown in the first embodiment has a two-layer structure of 803 and 806.
[0062]
The birefringent films 803 and 806 are different in the direction of the main axis of the refractive index. The first-stage birefringent film 803 having the polarization axis in the y-axis direction causes the optical shift in the x-axis direction and the second-stage birefringent film 806. Causes an optical shift in the y-axis direction.
[0063]
Two layers of λ / 2 birefringent films 804 and 805 are provided between the birefringent films 803 and 806. In order to reduce the wavelength dispersion, the polarization rotation operation is performed twice by performing the polarization rotation operation twice. Perform
[0064]
The organic EL panel 801 has the pixel 104 to be a light emitting layer, and emits light 807 having a predetermined light intensity and color according to image information. Since the emission light 807 is non-polarized light, a polarizing plate 106b having a polarization transmission axis in the x-axis direction is provided on the light emission side of the substrate, and the emission light 113 becomes a polarization light having a polarization axis in the x-axis direction. .
[0065]
The outgoing light 113 enters the birefringent film laminate 103 which is an optical pixel position shift unit.
[0066]
The polarized lights 113a and 113c emitted from the pixels in the i-th row and the (i + 2) -th row are subjected to a 90 ° polarization rotation operation by the polarization rotation layer 108, as in the first embodiment, and the polarization axis is converted to the y-axis direction. The birefringent films 803 and 806 in the next stage are optically shifted in the x-axis direction by the first birefringent film 803 having a polarization axis in the y-axis direction, and are optically shifted in the y-axis direction by the second birefringent film 806. A shift occurs.
[0067]
A 90 ° polarization rotation operation is performed by combining polarization rotation operations using two layers of λ / 2 birefringent films 804 and 805 between the birefringent films 803 and 806.
[0068]
The azimuth of the phase axis is set at 67.5 ° and 22.5 ° from the x-axis in the xy-axis plane, so that the polarization axis in the x-axis direction changes from 0 ° at the time of light incidence to at the time of emission of the birefringent film 803. 135 °, -90 ° when the birefringent film 806 is emitted, the polarization axis in the y-axis direction is converted from 90 ° to 45 ° at the time of light incidence to 0 °, and the polarization axis orientation is exchanged. As described above, by performing the 90 ° polarization rotation operation with the λ / 2 birefringent film layer in a multi-stage configuration, the phase compensation of the wavelength component deviating from the λ / 2 condition is performed. A wider band can be obtained than the operation of rotating the polarization axis by 90 ° by the 45 ° arrangement.
[0069]
FIG. 10 is a diagram showing the optical arrangement of the birefringent films 803 and 806 of the birefringent film laminate 103 in the present embodiment.
[0070]
In the birefringent film 803, the extraordinary ray refractive index n _e1 Is in the xz plane and has an angle θ with respect to the z-axis. ₁ Has formed. On the other hand, in the birefringent film 806, since the optical shift in the y-axis direction is performed as in the first embodiment, the extraordinary ray refractive index n _e2 Is in the yz plane and has an angle θ with respect to the z-axis. ₂ Has formed.
[0071]
FIG. 11 is a diagram schematically illustrating a method of assigning pixels and line-of-sight information according to the present embodiment.
[0072]
Here, for the sake of simplicity, an example is shown in which the number of parallaxes in the horizontal direction is 4 and the number of parallaxes in the vertical direction is 0. Further, the pixel array has a lattice shape, and a so-called square array is used.
[0073]
The pixels in the (i + 1) th row and the (i + 3) th row are subjected to a two-stage pixel shift by the birefringent films 803 and 806, and appear to move between the pixels in the ith row and the (i + 2) th row. That is, between the image information 1 in the line of sight displayed at the pixel of the i-th row and the j-th column and the image information 3 displayed at the pixel of the i-th row and the j + 1-th column, the image information 2 displayed at the pixel of the i + 1-th row and the j-th column Are overlapped and inserted. Therefore, the image information 2 to be displayed on the pixel at the (i + 1) -th row and the j-th column indicates the image information sampled at the pixel boundary between the i-th row and the j-th column and the i-th row and the j + 1-th column.
[0074]
FIG. 12 is a diagram showing a state of a light beam emitted from the lenticular lens array 802. For simplicity, similarly to FIG. 7, components of the organic EL panel other than the pixel structure, a birefringent film laminate, and the like are not shown.
[0075]
Here, since no vertical parallax is provided, the optical image selecting means is a lenticular lens array, and the lens center is located at the center of a pixel group to which a parallax number is assigned.
[0076]
Images (1 to 8) corresponding to eight viewing directions are emitted as light rays on a line connecting the pixel and the lens center.
[0077]
Compared with the conventional example in which no pixel shift is performed, the vertical resolution per line of sight is reduced to 視, but the number of lines of sight is doubled from four to eight.
[0078]
For example, assuming that the number of pixels in the horizontal direction of the organic EL panel is 1600 and the number of pixels in the vertical direction is 1200, in the conventional configuration, the number of parallaxes in the horizontal direction is 4, the number of display pixels per line of sight is 400 × 1200, and the aspect ratio is 4: 3. In this panel, the horizontal to vertical resolution ratio is 1: 4, but in this embodiment, the number of parallaxes in the horizontal direction is increased to 8, the number of display pixels per line of sight is 400 × 600, and the horizontal to vertical resolution is The ratio is 1: 2, which indicates that the resolution balance in the horizontal and vertical directions is improved.
[0079]
As described in the first embodiment, black display is performed on the pixel 401 located at the boundary of the pixel group, so that generation of a false image can be prevented.
[0080]
FIG. 13 is a diagram showing a desirable color arrangement when color pixels are used.
[0081]
When a color array is formed in a lattice shape, the pixel width in the horizontal direction and the pixel length in the vertical direction are often set to 1: 3, and a vertical stripe structure is often used. In the present embodiment, the pixels in the (i + 1) -th row are arranged between the pixels in the (i) -th row. It is desirable to take. Further, also in the column direction, it is desirable that the three RGB primary colors have a nested structure in the order of i row, i + 2 row, and i + 4 row. Therefore, it is desirable that such a pixel arrangement has a so-called oblique stripe structure in which adjacent pixels have different colors in the row and column directions as shown in FIG.
[0082]
In the above description, since the number of parallaxes in the vertical direction is set to 0 for simplicity, the slit array and the lenticular lens array are given as optical image selecting means. These may be a pinhole array and a lens array, respectively.
[0083]
【The invention's effect】
As described above, according to the embodiment of the present invention, the number of important horizontal parallaxes in the stereoscopic image display device is increased, and the resolution balance in the vertical direction and the horizontal direction in the image per line of sight is improved, thereby achieving high image quality. A high-quality stereoscopic image can be displayed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a configuration according to a first embodiment of the present invention when viewed from a side.
FIG. 2 is a cross-sectional view of the configuration according to the first embodiment of the present invention as viewed from the side.
FIG. 3 is a diagram showing an optical arrangement of a birefringent film according to the first embodiment of the present invention.
FIG. 4 is a diagram showing a pixel array and an optical shift direction of a pixel viewed from a z-axis direction in the first embodiment of the present invention.
FIG. 5 is a diagram schematically showing a method of assigning pixels and image information in the first embodiment of the present invention.
FIG. 6 is a diagram showing an example of display drive timing of a transmissive liquid crystal panel in the first embodiment of the present invention.
FIG. 7 is a diagram showing a state of a light beam emitted from a slit array in the first embodiment of the present invention.
FIG. 8 is a diagram showing an example of a desirable color filter array according to the first embodiment of the present invention.
FIG. 9 is a cross-sectional view of a configuration according to a second embodiment of the present invention as viewed from the side.
FIG. 10 is a diagram showing an optical arrangement of a birefringent film of a birefringent film laminate according to a second embodiment of the present invention.
FIG. 11 is a diagram schematically illustrating a method of assigning pixels and visual line information according to a second embodiment of the present invention.
FIG. 12 is a diagram showing a state of light rays emitted from a lenticular lens array according to the second embodiment of the present invention.
FIG. 13 is a diagram illustrating an example of a desirable color filter array according to the second embodiment of the present invention.
FIG. 14 is a diagram showing a method of assigning pixels and image information in a conventional configuration.
FIG. 15 is a diagram showing a state of light rays emitted from a slit array in a conventional configuration.
FIG. 16 is a diagram illustrating the display principle of the IP method.
[Explanation of symbols]
101 ... Transmissive liquid crystal panel
102 ・ ・ ・ Slit array
103 ... Birefringent film laminate
104, 401 ... pixels
105 ・ ・ ・ Light transmitting substrate
106a, 106b ... polarizing plate
108, 804, 805 ... λ / 2 wavelength film (polarization rotating layer)
109, 803, 806 ... birefringent film (optical shift layer)
110 ・ ・ ・ Glass substrate
111 ... light source light
112, 113a, 113b, 113c, 113d ... polarized light
114a, 114b ... incident light
115 ・ ・ ・ Outgoing light
601 ... opening
701: set of adjacent pixels
702... Color array set
801 ... Organic EL panel
802: Lenticular lens array
807 ・ ・ ・ Emission light
1500 ・ ・ ・ 3D image display device
1501 ... display object
1502 ・ ・ ・ Observer
1503, 1505... Object positions to be displayed
1504 ・ ・ ・ Display information
1506a, 1506b, 1506c, 1506d ... line of sight
1507a, 1507b, 1507c, 1507d ... object information display positions on the display screen

Claims (5)

Image display means in which a plurality of pixels are arranged in a plurality of rows,
Pixel selection means provided separately on the image display means, dividing the pixels on the image display means into a plurality of sets, and selectively transmitting light from the pixels,
The liquid crystal display device is provided between the image display means and the pixel selection means, has birefringence, and optically shifts a part of the pixels to form a pair of the two rows on the image display means. 3. A stereoscopic image display device comprising: a pixel shift means for one row. 2. The three-dimensional image display device according to claim 1, wherein the pixel selection unit is a pinhole array or a lens array. 2. The three-dimensional image display device according to claim 1, wherein pixels located at the boundaries of the plurality of sets of the pixels are displayed in black. The pixels on the image display means are arranged in a three-primary-color delta array, the three primary colors are sequentially circulated in the vertical direction, and the same color is adjacent to each other in the adjacent but not paired rows. The stereoscopic image display device according to claim 1. The pixel on the image display means has a square arrangement of three primary colors, the three primary colors are sequentially circulated in the vertical direction in the vertical direction, and the same colors are arranged in an oblique stripe arrangement. Stereoscopic image display device.

Images